# How to Measure the Height of a Tree or Object

Indirectly Measuring the Height of an Object can be
a challenging task. Many trees are too large to
measure with a handy little pocket tape, plus, how
do you manage your way through all the branches to
get an accurate reading. In this article I’m going
to go over how to measure the height of a tree using
an Abney level (like a hand level) and a clinometer.
The great part about using these tools is they are
inexpensive and can be used in many different
situations. All the principles below can also be
used to measure the height of a building, pole or
practically anything you need to measure from the
ground. The bad part is that you’ll have to remember
the Trigonometry you learned in high school, but
don’t worry, I’ll walk you through it so it’ll be a
breeze.

For each of these methods of measurement you will
need to know how far you are from the base of the
tree. This can be determined quickly and easily with
a measuring wheel or long measuring tape, preferably
an open reel measuring tape. To measure using a measuring wheel, simply
roll the wheel as you walk away from the base of the
tree. The counter will display the distance you’ve
traveled. For using the clinometer it is recommended
that you walk at least 1 to 1 and a half the height
of the tree.

Next we will need to use our clinometer to find out
the angle of elevation to the top of the tree. The
clinometer will feature an eye piece for you to look
through; this will display the angle of elevation.
Keep both eyes open and look at the top of the tree
with one eye and through the eye piece on the
clinometer with the other eye. The two images will
be transposed onto each other. Take note of the
angle of elevation. This will be used to determining
the height of the tree. It is represented by the
letter “A” on the reference picture below. (Please
remember that you will need to account for your
height unless you want to lie on the ground and
determine the angle from there.) Those two
measurements are all we need to plug into our
equation. Next we’ll use some trigonometry.

The first thing we need to do is to find the tangent
of the angle of elevation. The easiest way to find
this would be by using a calculator you could also
use a table of trigonometric functions. If you are
using a calculator push the “TAN” button and enter
the angle and then equals, the number now displayed
on the screen will be the TAN of the angle. Now
multiply that number by the distance you are from
the tree. The number you have now is the height of
the tree without (without your height). Simply add
the distance from the ground to the where you took
the measurements (your eye level to the ground in
most cases) and this will be the height of the tree.

Some clinometers have an easy feature built in to
help estimate height. Clinometers have scales that
display percent and distance (most come in feet but
some will have meters). With this method you will
still need to know your distance from the base of
the tree. It is easiest if you move the distance
away from the tree that the distance scale on your
clinometer is adjusted to. For instance, if it is
set at 66, which is the most common, it is suggested
that you move 66 feet away from the base of the
tree. The next step is too look at the top of the
tree the number indicated on your distance scale is
the height of the object you are looking at (minus
your height). Make sure you add your height to the
measurement this can be done by simply looking at
the base of the tree now and adding the two numbers
together or by a simple height measurement.

If you are working with the percentage scale it is a
little harder but still a relatively easy process.
First, find out your distance from the tree.
(Because the height of the tree is represented by a
percentage in comparison to your distance from the
tree you will need to be further away from the tree
than the height. 1 ½ the height of the tree is
recommended.) To find the height of the tree look
through the hand level and note the number on the
scale, it represents a percentage of the distance
that you from the tree. If it reads 100 then the
distance you are from the tree is the same as the
height of the tree. If it shows 50 than the tree
height is half the distance you are from the base of
the tree (minus your height). Next add you eye level
height to this measurement. If you want to double
check this measurement try doing the same steps from
multiple points around the tree. If the tree is
leaning the measurement will not be as accurate as
if it were straight. If you must measure a leaning
tree it is better to have the tree leaning to the
right or left as opposed to towards or away from
your position.

Engineer supply has many tools helping those working
in the forestry industry we have provided many
instruments to the nation forest service as well as
many local, state and national parks across the
nation. EngineerSupply looks forward to assisting
you with your forestry needs.

Copyright 2008 EngineerSupply